That is, by the way, why I qualified my statement with 'CPU-bound'. When the bulk of your program involves I/O, the overhead from array, hash, and stash lookups becomes negligible -- even for pipes, because they involve context switches to the process on the other end of the pipe.

$"=$,,$_=q>|\p4<6 8p<M/_|<('=>
.q>.<4-KI<l|2$<6%s!<qn#F<>;$,
.=pack'N*',"@{[unpack'C*',$_]
}"for split/</;$_=$,,y[A-Z a-z]
         {}cd;print lc
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